Program to find Sum of digits in C++

Written by

Juhi Kamdar

Many a times, we require to find the number of digits in a number or the sum of all digits of a number. In such cases, we can use the following method:


  1. First, save the number in another variable for future use.
  2. Now get the last digit of the number by using % operator. It will provide the last digit as remainder.
  3. We add it to the sum of all digits.
  4. Now, divide the Original number by 10, to trim the last digit. (This is possible as the data type is int)
  5. We repeat the above steps until all digits of the original number are summed up.


using namespace std;
int main()
int num,rem;
int duplicatenum=num;
int sum=0, count=0;
while(num!=0) // till all digits of num are dealt with
rem=num%10; //remainder,last digit extracted
sum=sum+rem; // add rem to sum
num=num/10; //trimming last digit from num
cout<<"Sum of "<<duplicatenum <<" is "<<sum;
cout<<"\nNumber of digits are:"<<count;

return 0; }


Sum of 4657 is 22
Number of digits are:4
Program to find Sum of digits in C++